The present invention relates generally to medical devices, and more particularly to an improved multi-lumen catheter.
Multi-lumen catheters are used for a variety of applications where it is necessary to have two or more separate fluid pathways. One such application for a multi-lumen catheter is for use in hemodialysis. During hemodialysis, a dual-lumen catheter can be employed to simultaneously accommodate opposing blood flow. More specifically, one lumen carries blood from a patient to a dialysis machine where it is processed for the removal of toxins, while the opposing lumen returns the purified blood to the patient.
Multi-lumen catheters are well known in the art. Dual lumen catheters, incorporating parallel D-shaped lumen to separate the blood flow and increase the rate of blood flow both into and out of the body, improved upon the use of multiple single lumen catheters. Subsequently, a third circular lumen was introduced to the dual lumen catheters to provide an additional inlet/outlet. Such a catheter can be seen in U.S. Pat. No. 5,797,869 to Martin. In Martin, the third lumen is located in the center of the internal septum, between the two semi-circular lumen. This configuration is intended to give the physician the option of simultaneously injecting a liquid medication during the dialysis procedure, an option not available with a simple dual lumen. However, locating a central lumen between the blood-carrying lumen compromises the reliability of blood flow. Another disadvantage in the catheters of the type described in Martin is that the inlet and outlet openings of the lumen are in close proximity to one another so that toxic blood and purified blood can mix, reducing the efficiency of the process.